This is a service page which covers ways of making useful bits and pieces of scientific equipment at home, or points to useful bits and pieces on other pages in this series. Some of the links here are to different pages, but the pages on sound and on sight and light things, both have a number of things for you to make.

How to make them

Making a simple balance
One of the more important forms of measurement involves weighing small things accurately. Sometimes you need to know an actual weight, which means calibrating your scales, and at other times, you only need to be able to compare two masses. Calibration is a problem I leave to you: this just deals with the basics.

You will need some cardboard, scissors, a drinking straw and some modelling clay or plasticine. You will be making a stand from cardboard, making a scoop at one end of the straw, adding some modelling clay/plasticine at the other end, pushing a needle through the straw at its balance point, closer to the clay end, and fitting it on the stand, then trimming the system until the straw rests horizontally.

The important thing is where the needle goes. The needle does not go through the centre-line of the straw, but through the straw close to the top, above the centre-line.

You can calibrate your balance in all sorts of units, using all sorts of standards, by noting how far one, two or three grains of sand (or whatever) tilt the straw against a carboard scale behind it. Over to you.

Making a stone blade
This is work in progress. I make basalt blades for fun, using basalt cobbles that I collect from a South Coast beach in New South Wales, Australia. You will need to amend these details to suit your stone.

The best basalt for the task is fine-grained stuff, and this seems to mean that it will always have fine bubble marks on the outside: I presume it cooled fast and that meant being close to the surface, and that meant low pressure which allowed bubbles to expand.

The best stones have diagonal planes of weakness through them -- I will try to add some photos to this section that may (or may not) show this. Then you take a larger stone in your left hand (if you are right handed), hold the blade stone in your right hand as though you are going to skim it, and bang it down sharply on the anvil stone.

If your stone is a good one, it may still take a dozen or more blows before it shears.
Small pieces may fly off, so safety goggles are a good idea, and stay away from other people.

This makes a crude sharp edge, which you can work further, if you wish: a common Australian aboriginal tool for this is a kangaroo tooth, or you can grind the edge on a piece of sandstone. Be warned: fresh edges will cut flesh very easily!

Once you have tried this, and especially if you have succeeded, you will know that anybody who looks down on "Stone Age people" as ignorant savages is talking through his or her hat.

And now for some help

How the balance works
The balance works because when it is balanced, half of the weight is on each side. If you add a few grains of sand, you increase the weight on that side, and so that side of the balance sinks.

Because you put the needle through near the top of the straw, this means that part of the straw moves across to the other side as the straw tilts, until a new balance is reached. If you put the needle closer to the centre-line of the straw, less of the straw moves to the other side as the straw tilts, and so the balance becomes more sensitive. If you put the needle below the centre-line, the balance becomes unstable and useless.

Getting the balance to sit in the middle when there is no weight means messing around with the clay or plasticine. You can either add or remove the clay, or you can move it towards or away from the needle.

No, I will not reveal my source of stone, but it is only just in the Sydney Basin. Some of the best tools I have seen were made not from basalt but from quartzite, but I still have to experiment with this stone: there could be an interesting project in studying different stones in your locality as tool-making material.

In Europe, of course, they use flint for this sort of work, but that stone seems to be hard to find in Australia.

This file is http://members.ozemail.com.au/~macinnis/scifun/making.htm, first created on January 27, 1998. Last recorded revision (well I get lazy and forget sometimes!) was on September 19, 2001.
Worried about copyright? You need to go look at my fine print. Well, maybe you don't after you read the next paragraph, but do it anyhow . . .and to see some more ideas, look at the start of that same page